Structure Cooling for Buildings

The problem we are solving is Access to Affordable & Sustainable Cooling. 

Indian cities are now 4-8C (7-13F) hotter in summer than just 40 years ago. Air conditioners are increasingly necessary, but are expensive to buy and need lot of electricity–hence also expensive to use. In India, where 800 million people depend on free food from the government for basic sustenance, ACs, no matter how energy efficient or low-cost, are completely unaffordable for the majority–and they suffer the health and productivity consequences of excessive heat. And this applies to at least 2 billion people across the world today who are poor and live in hot tropical areas.  

Structural Cooling makes cooling very affordable and thus accessible to all. It also saves 45-99% of electricity compared with AC, and thus promotes sustainability (mitigation AND adaptation), supports climate change resilience and enables Net Zero, Climate-Smart Buildings at scale.

While heatwaves will become increasingly common and fatal, heat even without heatwaves will negatively affect the health and productivity / livelihoods of over 1 billion Indians by 2040. While a small part of the population lives, works and studies in AC buildings, the vast majority use low income housing, government schools and hospitals, lower grade commercial buildings and government offices, railway and bus stations, factories and warehouses–facilities that are rarely air-conditioned. India is one of the three countries that are expected to exceed the limits of human survival due to heat conditions. Article: 

2.2 billion people could face heat waves beyond survival limit: National Academy of Science (https://www.hindustantimes.com...)

Multilateral agencies like the World Bank, UNEPs Kigali Cooling Efficiency Program etc. are focused on reducing the cost and increasing efficiency of refrigeration-based cooling. (https://www.cleancoolingcollab...). Such solutions, no matter how cheap, will remain unaffordable for nearly 2-3 billion people globally. People should not have to choose between food and cooling. Therefore, we need entirely different approaches to cooling.

Further, ACs use 20% of global electricity. The Indian AC market is expected to grow 42x by 2050, part of the reason that India will spend over $300 billion in new electricity generation capacity in just the next decade, including 80GW of new coal power capacity! The most energy-efficient ACs will remain expensive and thus adoption of five-star ACs today is under 20% and energy intensity of cooling will remain high.

We believe that cooling solutions that are 100x more affordable and also 100x more energy-efficient, are urgently required–at scale. And such solutions must be scaled up globally on a priority basis if we are to prevent heat epidemics and climate-induced collapse. The beautiful thing is that a technology exists–and has been proven for decades. It must be improved and adapted to various use cases, for ambitious goals. Therefore, a multi-pronged approach across innovation, finance, skilling, regulations and communications is needed to adopt it at scale for ALL buildings--so the poor are protected from heat, and the well-off reduce their carbon footprint.

Modern buildings, globally, are made of concrete and steel. When exposed to solar radiation, they accumulate and retain heat very efficiently, transfer this heat to indoor spaces, and thus create the need for indoor air conditioning.

The most energy-efficient cooling solutions, therefore, are ones that prevent the building structure from becoming hot in the first place. Green roofs, heat reflective paints and wall claddings are gaining acceptance, but currently have limitations in reliability, effectiveness, longevity, ease-of-maintenance and costs.

Flushing heat out from the building's structure is a robust, low-cost, controllable engineering solution, called Structural Cooling. Combined with fans, ventilation and above-mentioned solutions, it can provide comfortable indoors in any climatic condition. Lower capacities of AC can be added, where needed, and used when needed.

How does it Work? 

Structural Cooling is rather straightforward–especially for new buildings, but it can be retrofitted in existing buildings too.  

A network of special closed-circuit pipes is embedded in the building slabs during construction, and water (room temperature, not chilled) is run through these pipes continuously to absorb and remove heat from the concrete. Only a small pump is needed, hence it is an ultra-low energy system. It is closed-loop circulation, so water-efficient as well. And the pipes are embedded in the middle of the slab, so are not damaged by flooring repairs.

The case for retrofitting existing buildings is more complicated. Oorja has tested some solutions successfully, but they need further design and engineering to become market-ready.

Who is it for?

In the past few years, schools in Delhi gave special holidays in April and May as classrooms reached 42-44C, too hot for children to safely sit in. Public schools simply cannot afford ACs. Oorja implemented Structural Cooling for a school such that indoor temperatures are between 25-30 deg C, which is healthy and comfortable. 

The same can be done for various buildings that can become “heat shelters” during a heatwave.

Proven and Scaling.

Oorja has deployed over 30 large structural cooling projects for marquee customers, with zero complaints or leakages. In some, no AC is required so cost of cooling is reduced by 99%! In most, ACs are needed, but the load and usage are significantly reduced, so electricity (and emissions and O&M costs) fall by 40-70%. 

This knowledge is not proprietary, and anyone can learn it. Ideally, it should be mandatory and a part of municipal building codes so we significantly bend the electricity consumption curve and make Net Zero buildings commonplace.

Since ancient times, various solutions have been used to cool indoor spaces. Many of these solutions cannot easily be used in modern buildings, but Structural Cooling and other solutions (above) can cool buildings using very little electricity and at low upfront and operating costs. A multi-pronged effort is needed to deploy at scale–so we can protect the poor from heat, and reduce the carbon footprint of the better-off. 

Affordable AND sustainable cooling for All is the goal.

Structure cooling is ideal for modern masonry, concrete and steel buildings, especially in tropical climates, as such construction material absorbs and retains heat for a long period of time. 

The greatest beneficiaries are those who cannot afford conventional ACs. This includes at least a billion people in India, and possibly up to 2-3 billion worldwide. The earlier case of schools in Delhi is the perfect example. Heat affects their health and organs, and unplanned holidays disrupt learning and parents’ work schedules. Yet, public schools simply cannot afford air conditioning even though the cost of heat on that community is very very high. At a low cost of under USD 4 per square feet to install (<1-% of construction costs) and miniscule operating costs, the impact and cost - benefit is potentially huge!

Heat affects our mental health, making people angry, frustrated and even depressed and anxious. It affects our lungs, kidneys, heart and liver, placing excessive strain on them, affecting their performance and making existing health conditions worse. Over-heating leads to death-–as Europeans are also unfortunately discovering in heatwaves.

Low-income housing projects (slum rehabilitation) are cramped, densely packed buildings made with the cheapest materials and thinnest walls possible to cut costs. We have heard of people using sleeping pills to fall asleep because it is too hot. Factories and warehouses, government hospitals, railway stations and bus stations, are all areas where AC is unlikely to be properly deployed and where structural cooling can create a reasonably comfortable environment at an affordable cost. 

Once temperatures cross the wet bulb temperature, mass deaths result within hours, and we are coming closer to or crossing these thresholds increasingly often. These spaces can become “cool spots” for shelter during heatwaves. 

On the other hand, many who can afford ACs--higher-end residential and commercial buildings, malls, hospitals, hotels, schools / colleges and airports-–may find the cost of AC high but unavoidable. For them, structural cooling will reduce the cost of cooling, and also reduce their energy consumption and therefore carbon footprint. Large real estate owners can earn through carbon credits.

McKinsey’s GHG abatement cost curves show that efficient air conditioning costs $120 less than the median abatement solution (per tCO2e), making it one of the lowest cost, easiest to implement and hence a frontrunner to help fight heating and climate change. Nature published that SDGs related to education, healthcare, gender equality, and nutrition are at risk due to lack of indoor cooling, and “Embedding passive and energy-efficient sustainable cooling in urban infrastructure” is one of the best ways to help achieve SDGs.

The time has come for structural cooling to become a standard building system, so that those who can afford air conditioning need less of it and thus save money, and those who cannot afford it, still have comfortable and healthy spaces. At least 4 billion people live in warm and tropical areas and can benefit from Structure Cooling--out of which, for 2-3 billion, it may be the only affordable choice for cooling.

Oorja team of 36 people has strong engineering design and execution capability.  This team includes architects, HVAC engineers and designers, Site Supervisors, Procurement and Logistics, and Quality Assurance. We have delivered over 55 large projects for marquee clients like TATA Projects, L&T, IIM-Raipur, IP University, Delhi Government Department of Education, the Telangana State Renewable Energy Department, and the Indian Air Force. We have executed projects across India—from Ladakh, 18,000 feet high in the Himalayas, to Chennai in the hot south. We are exploring entering the MENA market.

About 30 of our 55 projects included structural cooling, in total covering 500,000 sq. ft.. These include offices, factories, warehouses, schools, aircraft hangars, and residential quarters—each of which have varied usage patterns and requirements, and therefore have to be optimized differently.

We have combined Structure Cooling with various other types of AC technologies including radiant cooling, geothermal cooling, maglev chillers etc. While 1 Ton of centralized AC normally services 250 sq. ft., our best building has a 1 Ton per 1,000 sq. ft. performance–amongst the best in the world.

Further, Oorja is recognized as the leading player for eco-friendly and low-energy cooling. We work with the leading architects and building MEP (Mechanical, Electrical and Plumbing) consultants and thus can bring together the entire ecosystem that is needed to maximize impact on the target audience.

Thus, we have experience in various geographic conditions, serving a variety of customer needs, with multiple technologies—and therefore are well equipped, along with our partners, to implement and promote Structure Cooling in India and globally.

As mentioned above, Oorja has deployed Structure Cooling in at least 30 large, commercial projects for a range of demanding clients. Possibly over 25,000 people use these buildings on a daily basis, and we would estimate that these structures use at least 45-70% less electricity than they otherwise would have (without structure cooling). The oldest systems have run effectively for nearly 10 years. Therefore, we are well past the stage of proving the technology.

But so far, our work has been for clients who explicitly wanted or needed an energy-efficient or sustainable solution. Mainstream real estate developers do not want additional responsibility of pursuing innovative solutions, nor additional costs, even if it reduces expenses for their tenants and customers and is good for the environment. Many HVAC consultants are also resistant to new solutions that they do not understand, and AC manufacturers who want to simply sell the maximum tonnage to boost their earnings, do not want structural cooling which will reduce demand for ACs.

Thus, there is a very very long way to go, and some opposition to overcome, to make Structural Cooling a default, required solution in every building—just like firefighting equipment or structural integrity is a standard requirement to get permission to construct a building.

For this, we are building an alliance of architects, structural engineers, HVAC consultants, Green Building experts, and academic institutions, to develop a pathway. This is new regulatory and advocacy territory for us, which is why a coalition is essential to ensure that all perspectives are included and the recommended solutions are practical and do not create other unintended side-effects. Some leading figures in the Green Building ecosystem, and some large builders are interested in pursuing this.

We want Structure Cooling to be widely adopted in all new and existing buildings in tropical regions. This will require efforts on various fronts–technology development, training, legal frameworks, technical standards for buildings, investment instruments and incentives, and communication efforts at a global ecosystem level. It will require bringing together relevant lessons from all parts of the world, and we believe that Solve can help us in these ways.

1. Supporting further product development and innovation around materials, devices, use-case designs, and construction techniques–esp for retrofits.

2. Interaction with policy makers on such low energy technologies.

3. Developing ways to train hundreds of architects and HVAC / MEP consultants to design these systems, and tens of thousands of plumbers to install these during the construction of a building and also as retrofits.

4. Local advocacy and raise capital for pilot projects in high-rise residential buildings and large public buildings.

5. Connects with industry bodies and thinktanks to build momentum for Structural Cooling, allied solutions, and Net Zero Buildings.

6. Working with Rating agencies and financial institutions to develop instruments that encourage energy-efficient choices.

7. Raising Grant and Blended Capital for all these activities.

MIT has the most respected engineering AND architecture departments in the world, and thus can bring together the best technical minds and expertise to help us further improve the performance of structural cooling systems. It will also bring tremendous credibility and authority to these efforts.

There is actually a lot of research at MIT around refrigeration and cooling across Material Sciences, Mechanical Engineering and Civil Engineering, which can help improve the performance and costs of these systems. Startups like Transaera and Smart Joules have come out of MIT in recent years, addressing different aspects of energy-efficient cooling. MIT faculty include several Indians, or those who work closely in India—including Bish Sanyal and Balakrishnan Rajagopal at DUSP—who would be very relevant to these efforts.

In recent years, the US has made some advances in regulations for energy-efficient buildings (equally, some efforts have not succeeded), and these can inform how we advocate in India and other countries. MIT has extensive experience creating collaborations in India through the TATA Centers and MIT-India Program, and MIT has helped set up various institutions in India including IITs and IIMs. Lessons from these can help us navigate the Indian system.

The MIT Center for Real Estate and Sloan School of Management have deep experience in financial instruments for green and sustainable buildings and cities.

Overall, we believe that Solve can truly help pull together high quality, relevant, and credible groups to support this effort. The non-monetary support is infinitely more important, and difficult for us to get, than the financial support (which, of course, is still appreciated). We would value the opportunity to be part of Solve even if no financial support is provided.

Most of the efforts to provide affordable cooling today focus on making a cheaper cooling device. All cooling devices are essentially designed to remove heat that has entered a space. 

Our approach is different–we are solving this problem by going to the root of the problem, which is the heat trapped in the building structure, which then heats up the indoor spaces. This is especially true in tropical climates where even residential buildings are constructed using concrete, masonry and steel, compared to most homes in the USA that are built using wood. These tropical buildings therefore store a lot of heat and transmit into the indoor spaces, and increase the need for cooling.

While there are many passive techniques to reduce the heat entering the buildings, they are not sufficient in the tropics due to significantly higher ambient temperatures. It is also difficult to deploy many passive techniques like shading devices, on multi-storied and high rise buildings–where all external heat (from solar radiation and ambient temperature) enters indoor spaces through structural elements (walls, windows, roof), and an active system to continuously remove the heat is the most efficient way to cool the space.

As building construction codes in most tropical countries today are not very stringent and therefore the building envelope is not highly efficient, many new buildings let in a lot of heat. Structure Cooling is an ideal solution in such cases as it does not require the building to use high efficiency construction materials or passive techniques. The solution will perform well even if a building is badly designed. As an engineered system, the performance can be controlled based on the input ambient or structural temperatures, to consistently achieve desired performance standards. Passive solutions do not offer such control and consistency.

Also, the low energy requirement for Structural Cooling allows rooftop solar to power the entire system.

We believe that Structural Cooling will increase interest in low-energy and no-energy cooling solutions, thereby changing how architects, real estate developers and property users / managers think about cooling, climate adaptability and Net Zero Buildings. We believe Net Zero Buildings can become a default solutions, and Structural Cooling will be an essential technology to accelerate the path to this goal.

>50% of the world’s population will live in the tropical region by 2050 and weather conditions of the tropics are expanding with the areas of subtropics. Warming climate will make access to affordable cooling comfort an absolute necessity in these regions. 

Most countries in these regions already face energy poverty with per capita electricity consumption ranging from 100-1500 KWH compared to a per capita consumption of nearly 13000 KWH for countries like the USA and UAE. Use of air conditioning will increase the per capita electricity consumption by 2-20x, depending on the country. The earth simply doesn’t have the resources for such an increase in electricity consumption and electricity prices already make air conditioning unaffordable in these countries. 

So, an affordable and low energy cooling system that can possibly be powered by renewable energy is a need that many in these regions already have and this demand is expected to increase exponentially in the coming years. While air conditioning is definitely not the solution due to the energy poverty and cost of electricity prices, other low cost cooling devices compromise on their useful life as they do not last more than a few seasons. 

Therefore, a low cost, low energy, long lasting cooling system that can be powered by renewable energy is the ideal solution for cooling needs of tropical regions. At scale, Structure Cooling will cost less than USD 2/sq.ft and less than 0.05 KW/Ton of cooling compared to a consumption of 1.2 KW/Ton by an average air conditioner. 

Tropical regions will also witness significant growth in construction of new buildings and we plan to engage with multiple partners to train the plumbers in these regions to install structure cooling during a building’s construction. The pipes used in structure cooling last more than the building’s life and hence, will not need to be changed every few seasons. While it will not provide the comfort conditions similar to air conditioning, it will provide indoor temperature conditions between 25-30 deg C most of the time. Such indoor temperature conditions provide sufficient comfort, especially when outdoor temperatures are above 40 deg C.

Our impact goal is to ensure “affordable AND sustainable cooling for All.”

Thus, the key impact metrics are:

1. Number of people getting access to cooling comfort, who otherwise would not

2. Electricity usage avoided compared to air conditioners

3. % of electricity for cooling from clean renewable energy

4. CO2 emissions avoided compared to air conditioners

Buildings are responsible for 40% of the global CO2 emissions compared to 20% from the transport sector. This share of CO2 emissions is likely to increase as new buildings are constructed in many economies and usage of air conditioning increases by 10-40x in the next 25 years in tropical countries. 

Residential air conditioning sales will constitute nearly 75% of the overall sales and most of the electricity demand from the residential sector will be during non-solar hours, at night.Renewables will require large investment in expensive energy storage systems, which is not viable today in many of these economies, leading to increased usage of fossil fuels-based electricity generation. Structure cooling will eliminate or significantly reduce electricity demand at night. This will allow an easier and shorter path to achieve the building sector’s decarbonisation and Net Zero goals. 

1. Number of people getting access to cooling comfort, who otherwise would not

While this is easy to track for projects implemented by Oorja or our partners, it is a difficult metric to track globally and will require a central repository of all buildings using Structural Cooling, and the nature tenants / usage. If a global alliance is created or through partnership with organizations like USGBC etc, it will be possible to track most, but not all, projects, and get this data at a global level.

2. Electricity usage avoided compared to air conditioners

Well accepted building models used by Green Building consultants and HVAC designers help to predict the cooling requirement and electricity consumption. These models can be used to compute the estimated electricity saved by using Structural Cooling.

3. % of electricity for cooling from clean renewable energy

If an on-site solar panel is used to power the Structural Cooling system, it is easier to monitor what percentage of energy for cooling is through renewable energy. If the facility receives some share of renewable energy through the grid or captive contracts, then details of energy composition will be needed from the asset owner to calculate this metric. Where Oorjs develops projects, we have access to this information and can get detailed information including trends based on time of the year as cooling requirement, and renewable energy generated, vary through the year.

4. CO2 emissions avoided compared to air conditioners

This can easily be calculated from No 2 and 3 above.

In addition, there are other impacts that are difficult to monitor. Structure Cooling can operate with natural ventilation and therefore helps maintain healthy indoor air quality, while split AC units that are common in tropical economies do not allow any ventilation, which leads to build up of CO2 and other gases that are unhealthy for people.

The core of the technology is based on the traditional tropical architecture which either used various shading techniques or thick walls (2-4 ft.) to prevent inner wall surfaces becoming warmer than 30 deg C. Human skin temperature is between 32-34 deg C and can radiate heat to surfaces with lower temperature to feel comfortable. Various construction techniques like trombe walls, jaalis, stone masonry, large roof overhangs, recessed external walls etc. have been used to keep the walls of the living spaces from getting heated up. 

Such construction techniques are not possible in the high rise building construction where most of the population in the tropical countries is expected to live. This has led to inner wall surfaces to be in excess of 35 degrees even at night, with summer temperatures often exceeding 40 deg C. Therefore, an active cooling system is needed. 

Structure cooling achieves this by embedding a network of pipes in the building structure during its construction (or using false ceiling panels for retrofit) and circulating water in the piping network to remove the heat from the building structure. Since the temperature of the circulating water is between 24-26 deg C, the surface temperatures always remain below 30 deg C proving comfort with the use of a fan and natural ventilation.

These are PERT/PEX pipes and are commonly available from Europe and China, but they are not manufactured locally. A small pump, typically consuming 0.5 to 4 KW  is used to circulate the water, and the pipes are run through a water body like a water tank, swimming pool or a thermal mass to discharge the accumulated heat. 

For existing buildings, more product development is needed. Panels with embedded pipes can be installed instead of standard false ceilings, or bolted to the ceiling, to absorb and remove heat. Prototypes have been tested by Oorja, but these need to be engineered into saleable products.

At scale, the cost of deploying Structural Cooling can come down by 40-50% from today’s prices due to economies in logistics and development of purpose-specific devices like pumps and valves. Design innovation can drop costs further. Today, Structural Cooling would add about 7-10% to the overall construction cost of a building. This can be reduced by 3-4% of construction cost.

IoT sensors can be used to centrally monitor the performance of Structural Cooling systems to improve their efficiency. Due to the ultra-low energy usage and zero water consumption, however, it is difficult to make the system more resource-efficient. But operating performance can be improved by changing the pressure or temperature of water, to adjust to hotter and cooler weather, and the data can also help develop other solutions and technologies to make every building Net Zero.

There are multiple installations of this technology in India.

Oorja has 36 full-time staff at this time. We hire consultants when needed, and local contractors to execute the civil work for our projects. In various ways, all of them are involved in designing and executing structural cooling solutions, which is a part of most of the projects we undertake.

All the senior people at Oorja, in customer and project development, design and engineering, project management and quality assurance, will be part of this effort. We will bring in new staff with experience in advocacy, communications and project management, so we can work more effectively with collaborators on this effort.

We have been working on this solution for the last 5 years. 

There are certain dimensions where we can be proud of our diversity, and some where we are not.

Although based in Hyderabad, we work across India and therefore have team members from geographically diverse areas. Being a technical business, however, most of our staff are well educated and from urban centers—but many of our site supervision staff have technical diplomas (rather than engineering degrees) and come from low income groups. We provide a good working culture where people can take responsibility and rise up without discrimination.

Being in the infrastructure / construction projects business, and located a little outside Hyderabad in an industrial zone, gender diversity is harder to develop. We have interviewed women for various roles, but they have found the location and commute, male-dominated industry, need for travel to customer construction sites (where one can easily feel unsafe) etc, difficult to accept. There is zero gender pay discrepancy in our organization.

In this industry, women often take on roles as architects, researchers, in B2C sales and marketing, and human resources management—but we do not have many such roles. While we regularly have women as interns and for student projects, it has been difficult to recruit them for full-time roles for the above reasons. Covid also drove people to seek “safer” work conditions, often closer to their hometown–and this has made it harder for us to recruit the right talent, which also affects our ability to build the kind of diverse team we would like. The E-CaaS business, as against EPC projects, requires a more varied skillset including data scientists, O&M Supervisors, investment managers, customer relationship managers etc, and we expect to build a more diverse team that should look quite different in 2-3 years compared with today.

While we do not believe that there are structural barriers within the business that limit opportunity, better management practices, clearer targets and KPIs for each employee, training programs, appraisal process etc, will create more opportunity for our staff and objectivity in how we assess them. These are things we need to prioritize, and are raising capital from investors and bringing in new talent, to aid this transformation.

Oorja’s business model is very simple. We work on a EPC (Engineering, Procurement and Commissioning) model wherein we design the system, buy the equipment and install it for the client, and are paid based on milestones. After commissioning, we do quarterly AMC visits, but all O&M activities are done by the client or a facility management firm. The Structural Cooling system is installed and paid for as part of the EPC contract.

Going forward, Oorja is also innovating the Energy-efficient Cooling-as-a-Service model (E-CaaS) in India, wherein we will design, invest in and install the entire cooling system for the client, and the client pays for the cooled air based on their usage through a 15-year contract. Large users of cooling, like hospitals, large office buildings, malls, temperature-controlled warehouses and even hotels, are ideal clients for this and the first two projects will be implemented in this quarter itself. 

E-CaaS allows the client to adopt energy-efficient cooling without any upfront cost, and the low O&M expenses saves the client 30-40% in lifecycle costs. Large buildings with high credit worthiness are suitable clients—big corporates and REITs / real estate investors will be the main customers. 

Some others will prefer to buy the equipment and operate it themselves as it gives a sense of control or allows integrated building operations. Most such clients do not have the specialized staff to run these systems well, so we can provide our intelligent off-site analysis and monitoring systems that use real-time data to help such clients optimize operations and maximize savings. 

Ultimately, E-CaaS is simpler and cheaper, and hence attractive to clients, but Oorja will not be able to serve low-credit customers. Blended capital, Impact Investors and other structures could be used to make Structural Cooling available to such buildings and clients–which is where Solve can help develop the right financing instruments and structure.

Oorja is a profitable business with $1.5 million in revenue and about $250,000 in EBITDA for financial year 2023-24 (April 2023 – March 2024). The EPC team will continue to scale as we get larger contracts, including for airports and other infrastructure projects, and will raise working capital (debt) to scale the business.

E-CaaS projects requires significant capital, so we are raising equity from investors and debt from equipment leasing firms to finance the equipment to set up new projects. The first two projects require $1.4 Million in equity and debt (which is nearly lined up at this time).

Lower credit customers or government entities, however, are not attractive for investors as perceived risk is very high. Structural cooling can be offered in such a E-CaaS model as well, but blended capital, social / impact finance or Environmental Impact Bonds could be new financial instruments we can use to finance these projects. Solve’s support in such financial innovations would be useful.